Electrode, membrane electrode assembly, electrochemical cell, and stack

Abstract

An electrode of an embodiment includes a base material, and a catalyst layer provided on the base material and having a porous structure. When a sum of heights of all peaks belonging to Ir oxide is I0, the height of a peak of IrO 2 (110) is I1, and the height of a peak of IrO 2 (211) is I2, a ratio of (I1+I2)/I0, which is a ratio of spectra obtained by X-ray diffraction measurements using Kα rays of Cu in the catalyst layer, is 50% or more and 100% or less in a range of a diffraction angle of 20 degrees or more and 70 degrees or less.

What is claimed is: 
     
       1. An electrode comprising:
 a base material; and 
 a catalyst layer provided on the base material and having a porous structure, 
 wherein the catalyst layer comprises IrO 2 , 
 wherein, when a sum of heights of all peaks belonging to Ir oxide is I0, a height of a peak of IrO 2  (110) is I1, and a height of a peak of IrO 2  (211) is I2, a ratio of (I1+I2)/I0, which is a ratio of spectra obtained by X-ray diffraction measurements using Kα rays of Cu in the catalyst layer, is 100% in a range of a diffraction angle of from 20 degrees to 70 degrees, and 
 wherein no other peak belonging to IrO 2 , excluding the peak of IrO 2  (110) and the peak of IrO 2  (211), is included in the spectra obtained by X-ray diffraction measurements using Kα rays of Cu in the catalyst layer. 
 
     
     
       2. The electrode according to  claim 1 , wherein when a sum of heights of all peaks belonging to Ir metal is I3, a ratio of I3/I0, which is a ratio of spectra, is from 0% to 5%. 
     
     
       3. The electrode according to  claim 1 , wherein a crystallite size of the catalyst layer is from 2 nm to 15 nm. 
     
     
       4. The electrode according to  claim 1 , wherein a porosity of the catalyst layer is from 50 vol % to 95 vol %. 
     
     
       5. The electrode according to  claim 1 , wherein a thickness of the catalyst layer is from 2 nm to 500 nm. 
     
     
       6. The electrode according to  claim 1 , wherein the catalyst layer comprises from one layer to 30 layers. 
     
     
       7. The electrode according to  claim 1 , wherein the catalyst layer further comprises a noble metal or a noble metal oxide comprising at least one noble metal element selected from the group consisting of Pt, Ru, Rh, Os, Pd, and Au. 
     
     
       8. The electrode according to  claim 1 , wherein the catalyst layer further comprises a non-noble metal or an oxide comprising at least one element selected from the group consisting of Ni, Fe, Mn, Al, Zn, Ta, W, Hf, Si, Mo, Ti, Zr, Nb, V, Cr, and Sn. 
     
     
       9. A membrane electrode assembly comprising the electrode according to  claim 1 . 
     
     
       10. An electrochemical cell comprising the membrane electrode assembly according to  claim 9 . 
     
     
       11. A stack comprising the electrochemical cell according to  claim 10 . 
     
     
       12. The electrode according to  claim 1 , wherein, when a sum of heights of all peaks belonging to Ir metal is I3, a ratio of I3/I0, which is a ratio of spectra, is 0%. 
     
     
       13. The electrode according to  claim 1 , wherein the catalyst layer consists of iridium oxide.